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9/22/2017 12:11:25 AM
Posted: 2/21/2006 3:55:09 PM EDT
[Last Edit: 2/25/2006 3:35:13 PM EDT by Jason280]
I did a little chrono work the other day, and thought I would share my results.

17 Feb 06
Temp: 68* and sunny
Chrono 10' from muzzle

16" DPMS M4gery

Rem UMC 55gr FMJ 2873 2873 2842 2855 2812 2855 2873 2861
Avg: 2855 SD: 20.7

WCC '86 (Q3131?) 3065 2976 3016 2969 2996
Avg: 3004 SD: 38.5

PMP South African 55gr FMJ 2989 2962 3009 2930 2949
Avg: 2967 SD: 31.4

IMI 5.56 (Q3131 spec?) 2861 2911 2836 2886 2830
Avg: 2864 SD: 34.05

Wolf 62gr Polymer 2704 2704 2699 2635 2699
Avg: 2688 SD: 29.8
***throw out low velocity (2635)***
Avg: 2701 SD: 2.8

WCC Q3131A 55gr 3086 3125 3115 3086 3129
Avg: 3108 SD: 20.8

WCC Q3131 55gr 3115 3122 3108 3079 3065
Avg: 3097 SD: 24.5

Malaysian M193 '84 3137 3182 3167 3174 3212
Avg: 3174 SD: 27

Winchester White Box 45gr HP 3267 3182 3244 3079 3100
Avg: 3174 SD: 83.8 *highest recorded


18" Armalite DCM barrel

Malaysian M193 '84 3236 3212 3226 3220 3252
Avg: 3229 SD: 15.4

Wolf 62gr Polymer 2732 2754 2754 2818 2836
Avg: 2778 SD: 45

WCC '86 3037 3093 3129 3129 3100 3079 3030 3100 3093 3065
Avg: 3085 SD: 33

Winchester White Box 45gr HP 3252 3228 3197 3212 3252 3392 3401 3292
Avg: 3278 SD: 78

Average accuracy was around 2" for just about all the loads. The most accurate load was the Winchester White Box 45gr HP's, which also had the highest standard deviation. The most inaccurate load was the Malaysian M193, which consequently had the highest average muzzle velocity. One interesting note is the Wolf Polymer, which I've chrono'd before and recorded single digit standard deviations in the past. However, accuracy was and still is mediocre.

Another interesting note is the SD's of the ammo stayed fairly consistent between the 16" and 18" barrels, and acuracy was similar in both guns. However, the best group was around 3/4" with the 45gr HP's in the 18" DCM barrel.


Link Posted: 2/21/2006 4:21:50 PM EDT
What was the twist rate on the barrels, or are you gonna make me look it up?
Link Posted: 2/21/2006 5:04:44 PM EDT
Damn, didn't even think about that. The DPMS has a 1/9 and the Armalite is a 1/8" twist.
Link Posted: 2/21/2006 7:21:30 PM EDT
I have some data to add. I can't figure out why XM193 is so hot out of my gun. I'm thinking it might be a hot LOT# of LC or something.



Rifle: Colt 6520, 16", 1/7, chrome lined chamber & bore. M16 carrier.
Chrono: Alpha Master Chrony.
Setup: 10ft from muzzle.
Weather: 79, sunny. Elevation less than 100ft. Slightly humid.


Federal XM193 55gr LOT-105

3294
3212
3268
3246
3225

Average: 3249
SD: 33


Chrono reads perfect with all other calibers. Barrel was not hot on the Colt. Rounds were not left in chamber to cook. I thought a 16" was suppose to be 100-120fps less than these numbers?


Link Posted: 2/21/2006 7:49:39 PM EDT
Damn thats some hot ass lc.
Link Posted: 2/21/2006 8:17:29 PM EDT
Yeah I know, I am starting to get concerned. There were no pressure signs on the brass or primer, none at all. Maybe I am just being paranoid. Either way, it is kinda cool to get rifle velocities out of a carbine.


Maybe someone who's an expert will post knowing something I don't.
Link Posted: 2/22/2006 12:07:37 PM EDT
Sounds like you have a good load going. How accurate has it been?
Link Posted: 2/22/2006 12:33:59 PM EDT
?
Link Posted: 2/22/2006 1:17:53 PM EDT
Good report, thanks for sharing.
Link Posted: 2/22/2006 4:54:28 PM EDT
Thank you for sharing!!!
Link Posted: 2/23/2006 4:00:34 PM EDT
No problem. I'm working on a trade for a 24" Savage right now, so I should be able to post velocities out of a 24" tube before long.
Link Posted: 2/23/2006 4:58:06 PM EDT
[Last Edit: 2/23/2006 5:14:07 PM EDT by AtlantaFireman]

Originally Posted By Dont-Tread-On-Me:
I can't figure out why XM193 is so hot out of my gun. I'm thinking it might be a hot LOT# of LC or something.



Since these are from Lake City and made to meet U.S. military specs, it could be the bullet jacket allowing higher velocity: lower friction. Other than that possibility, you may have one HOT lot.
Link Posted: 2/23/2006 5:10:55 PM EDT

Originally Posted By Jason280:
One interesting note is the Wolf Polymer, which I've chrono'd before and recorded single digit standard deviations in the past. However, accuracy was and still is mediocre.



Several high masters I know shoot Russian primers specifically because the primers are extremely consistant: better than Federal Gold or CCI Bench Rest. I've seen strings of 10 shots, in .308, giving a standard deviation in the low teens and single digits, using an Ohler 35.

Russian bulk bullets are not known for accuracy; its all about high numbers and full auto. Russian match bullets are some of the best...when you can FIND them outside of Mother Russia.

Side note:
I wish that we could import Swiss GP90 again, and get Finn 5.56mm. Those two countries believe in very accurate issue ammo.

Thanks for your work. It is not easy taking the time to set up a chrono and shoot for it: takes a long time.
Link Posted: 2/25/2006 3:34:44 PM EDT
Here's some results I dug up from a shoot back in December (some from a 22" barrel).

Barrel Length: 16.5"
Temperature: 48*
Chrono 12 feet from muzzle

Malaysian M193, '84 Head stamp (16.5" bbl)
3074 3086 3065 3058
avg: 3071
SD: 12.09
med: 3069.5

Malaysian M193, '84 Head stamp (22" bbl)
3276 3292 3252
avg: 3273
SD: 20
med: 3276

Accuracy was around 1.75-2" @ 100 yards


Winchester Q3131
3037 2987 3044
avg: 3022
SD: 31
med: 3037

South African PMP .223
2801 2766 2812
avg: 2793
SD: 24
med: 2801

Wolf Polymer
2666 2666 2661
avg: 2664
SD: 2.8
med: 2666


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